Guys, maybe it's a stupid question, but I really cannot jump high on those blocks! How do you do that? I can jump like one time in 50 attempts. The correct jump is like double jump (the first one's tiny, the second one's really high).

It comes down to timing the first of the two jumps that make a double jump.

Preface: I don't play Nv2, this info is for 1.4, but may apply.

Scenario: The ninja falls onto a bounce block

You have a few options to make your first jump while you push the bounce block down, then ride it back up1. Jump while you are pushing the bounce block down2. Jump when the bounce block is at it's lowest point, turning around3. Jump while the bounce block is moving back upwards

Then, you have a choice of when to make your second jump.

The best way to learn is by trying it, but I'll give you a good place to start. Do not jump until the bounce block is at the bottom, then make your second jump as soon as you can. You really want to just hit the jump key twice in quick succession (think double clicking).

Once you can consistently make a simple double jump, you will slowly learn to tweak the timings to get different results.

And finally, at least in 1.4, the behaviour of a bounce block while you push it is completely different when you are moving left/right vs. falling straight onto it without any keys. Experiment with horizontal movement while you're standing on the block.